The present invention is directed to the production of esters by functionalizing polymer olefins in a batch carbonylation process. In particular it is directed to a rapid high conversion Koch batch process using an acid catalyst and a hydroxylic trapping agent under conditions that readily produce a predominantly ester-functionalized polymer.
The present invention is directed to an improved polymer functionalized by the Koch reaction more particularly by reacting at least one carbon--carbon double bond with carbon monoxide in the presence of an acidic catalyst and a nucleophilic trapping agent to form a carbonyl or thiocarbonyl functional group, and derivatives thereof.
The term "polymer" is used herein to refer to materials comprising large molecules built up by the repetition of small, simple chemical units. In a hydrocarbon polymer those units are predominantly formed of hydrogen and carbon. Polymers are defined by average properties, and in the context of the invention polymers have a number average molecular weight (Mn) of at least 500. The term "hydrocarbon" is used above herein to refer to non polymeric compounds comprising hydrogen and carbon having uniform properties such as molecular weight. However, the term "hydrocarbon" is not intended to exclude mixtures of such compounds which individually are characterized by such uniform properties. Both hydrocarbon compounds as well as polymeric compounds have been reacted to form carboxyl group-containing compounds and their derivatives. Carboxyl groups have the general formula --CO--OR, where R can be H, a hydrocarbyl group, or a substituted hydrocarbyl group. The synthesis of carboxyl group-containing compounds from olefinic hydrocarbon compounds, carbon monoxide, and water in the presence of metal carboxyls is disclosed in references such as N. Bahrmann, Chapter 5, Koch Reactions, "New Synthesis with Carbon Monoxide" J. Falbe; Springer-Verlag, New York, 1980. Hydrocarbons having olefinic double bonds react in two steps to form carboxylic acid-containing compounds. In the first step an olefin compound reacts with an acid catalyst and carbon monoxide in the absence of water. This is followed by a second step in which the intermediate formed during the first step undergoes hydrolysis or alcoholysis to form a carboxylic acid or ester. An advantage of the Koch reaction is that it can occur at moderate temperatures of -20.degree. C. to +80.degree. C., and pressures up to 100 bar.
The Koch reaction can occur at double bonds where at least one carbon of the double bond is di-substituted to form a "neo" acid or ester ##STR1## (where R' and R" are not hydrogen).
The Koch reaction can also occur when both carbons are mono-substituted or one is monosubstituted and one is unsubstituted to form an "iso" acid (i.e. --R'HC--COOR). Bahrmann et al. discloses isobutylene converted to isobutyric acid via a Koch-type reaction.
U.S. Pat,. No. 2,831,877 discloses a multi-phase, acid catalyzed, two-step process for the carboxylation of olefins with carbon monoxide.
Complexes of mineral acids in water with BF.sub.3 have been studied to carboxylate olefins. U.S. Pat. No. 3,349,107 discloses processes which use less than a stoichiometric amount of acid as a catalyst. Examples of such complexes are H.sub.2 O.BF.sub.3.H.sub.2 O, H.sub.3 PO.sub.4.BF.sub.3.H.sub.2 O and HF.BF.sub.3.H.sub.2 O.
EP-A-0148592 relates to the production of carboxylic acid esters and/or carboxylic acids by catalyzed reaction of a polymer having carbon--carbon double bonds, carbon monoxide and either water or an alcohol, optionally in the presence of oxygen. The catalysts are metals such as palladium, rhodium, ruthenium, iridium, and cobalt in combination with a copper compound, in the presence of a protonic acid such as hydrochloric acid. A preferred polymer is polyisobutene, which may have at least 80% of its carbon--carbon double bonds in the form of terminal double bonds. Liquid polyisobutene having a number average molecular weight in the range of from 200 to 2,500, preferably up to 1,000 are described.
U.S. Pat. No. 4,927,892 relates to reacting a polymer or copolymer of a conjugated diene, at least part of which is formed by 1,2 polymerization, with carbon monoxide and water and/or alcohol in the presence of a catalyst prepared by combining a palladium compound, certain ligands and/or acid except hydrohalogenic acids having a pKa of less than 2. Useful Lewis acids include BF.sub.3.
Although there are disclosures in the art of olefinic hydrocarbons functionalized at the carbon--carbon double bond to form a carboxylic acid or derivative thereof via Koch-type chemistry, there is no disclosure that polymers containing carbon--carbon double bonds, including terminal olefinic bonds, either secondary or tertiary type olefinic bonds, could be successfully reacted via the Koch mechanism. Additionally, it has been found that the process of the present invention is particularly useful to make neo acid and neo ester functionalized polymer. Known catalysts used to carboxylate low molecular weight olefinic hydrocarbons by the Koch mechanism were found to be unsuitable for use with polymeric material. Specific catalysts have been found which can result in the formation of a carboxylic acid or ester at a carbon--carbon double bond of a polymer. Koch chemistry affords the advantage of the use of moderate temperatures and pressures, by using highly acidic catalysts and/or careful control of concentrations.